Second-harmonic generation in the air-based femtosecond plasma under loose focusing
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We used filamentation of 940 nm, 90 fs, up to 6.5 mJ pulse to measure the spatial and spectral distributions of the second harmonic with 10^{-9} conversion efficiency in comparatively long focusing geometry (40 cm and 100 cm focal lengths, ≥1 cm filament), as... ...
